1. Field of the Invention
The present invention relates to an ink-jet head that ejects ink to print a desired image on a recording medium.
2. Description of Related Art
Japanese Patent No. 2992756 discloses an ink-jet head in which an ink chamber, referred to as a reservoir, communicating with a plurality of supply paths each formed with a pressure chamber and a nozzle is provided within a substrate. In this ink-jet head, the substrate and an ink tank separately disposed at the outside of the substrate are connected with each other via a connecting passage so that ink is supplied into the reservoir. The ink supplied to the reservoir passes through the respective supply paths and is ejected from each nozzle. Protrusions for branching ink are formed in the reservoir The protrusions prevent air bubbles from being stagnant in the reservoir.
Japanese Patent Laid-Open No. 9-262980 discloses an ink-jet head in which ink is supplied from an ink chamber, referred to as a manifold channel, to a liquid chamber facing a piezoelectric element, and then ejected from a nozzle opening. In this ink-jet head, ribs are disposed in the manifold channel in order to prevent generation of air bubbles in the manifold channel to realize that ink has a uniform passage resistance until reaching each liquid chamber.
Japanese Patent Laid-Open No. 6-218919 discloses an ink-jet head in which ink supplied from an ink supply hole is distributed from an ink chamber, referred to as a reservoir, to a plurality of passages each extending to a nozzle. In this ink-jet head, a substrate constituting the passages and the reservoir, and a second substrate formed with protrusions are laminated with each other. Since the protrusions having a high dimensional accuracy formed on the second substrate are inserted into the passages in the substrate, a stable dimensional accuracy of the passages can be obtained.
None of the above-mentioned ink-jet heads are constructed by bonding two units, by applying pressure thereto, each formed therein with a ink passage such that their ink passages may connect with each other. These references do not disclose that, in the ink-jet heads, a reduction of the pressure and irregularities in application of pressure during bonding two units by applying pressure thereto cause a defective bonding between the units.